INTRAOPERATIVE END-TIDAL CARBON-DIOXIDE VALUES AND DERIVED CALCULATIONS CORRELATED WITH OUTCOME - PROGNOSIS AND CAPNOGRAPHY

Objective: To determine how much information concerning resuscitation and outcome is provided by the end-tidal CO2 and derived variables obtained during surgery, Design: Retrospective chart review, Setting: Emergency hospital operating room, Patients: One hundred critically ill or injured patients requiring major surgery and having a mortality rate of 41%, Interventions: Standard intraoperative monitoring, including continuous capnography, plus arterial blood gas analyses every 1 to 1.5 hrs during surgery, Measurements and Main Results: There was only a fair correlation between the PaCO2 and end-tidal CO2 (r(2) = .14), The mortality rates in these patients were highest in those patients who had the lowest end-tidal CO2 values, the highest arterial to end-tidal CO2 differences, and the highest estimated alveolar deadspace fraction, A persistent end-tidal CO2 of less than or equal to 28 torr (less than or equal to 3.8 kPa) was associated with a mortality rate of 55% (vs, 17% in those patients with a higher end-tidal CO2), The mortality rate was also increased in patients with a persistent arterial to end-tidal CO2 difference of greater than or equal to 8 torr (greater than or equal to 1.1 kPa) (58% vs, 23%). Conclusions: End-tidal CO2 and derived values should be monitored closely in critically ill or injured patients, Efforts should be made-by increasing cardiac output and core temperature and by adjusting ventilation as needed-to maintain the end-tidal CO2 at greater than or equal to 29 torr (greater than or equal to 3.9 kPa) and the arterial to end-tidal CO2 difference at less than or equal to 7 torr (less than or equal to 1.0 kPa).